458.Last position of target

1.Description:

Find the last position of a target number in a sorted array. Return -1 if target does not exist.

Example

Given[1, 2, 2, 4, 5, 5].

For target =2, return 2.

For target =5, return 5.

For target =6, return -1.

2.Code

public int lastPosition(int[] A, int target) {
       if(A==null || A.length==0){
           return -1;
       }
       int start=0,end=A.length-1;
       while(start+1<end){
           int mid=start+(end-start)/2;
           if(A[mid]==target){
              start=mid; 
           }
           else if(A[mid]>target){
               end=mid;
           }
           else{
               start=mid;
           }          
       }
       if(A[end]==target){
           return end;
       }
       if(A[start]==target){
           return start;
       }
       return -1;
    }